Musannaf Ibn Abi Shaybah

Hazrat Harith bin Barza says that Hazrat Khubaib was brought and sold in Makkah. When the polytheists took him out of the Haram to kill him, he said, "Let me perform two rak'ahs (units of prayer)." The polytheists allowed him, so he performed two rak'ahs. Then he said, "If I had not feared that you would say I prolonged the prayer out of fear of death, I would have performed an even longer prayer."